<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .box{
            width: 200px;
            height: 200px;
            border: 1px solid #f60;
            float: left;
            margin: 20px;
        }
        .active{
            background: yellow;
        }
    </style>
</head>
<body>
<input type="button" class="btn" value="删除类名">
    <div class="box"></div>
    <div class="box"></div>
    <div class="box"></div>
</body>
</html>
<script src="js/jquery-1.10.1.js"></script>
<script>
    $(function () {
        //点击添加类名
        $(".box").click(function () {
            //给当前正在点击元素添加类名
            $(this).addClass("active");
        });
        //点击删除类名
        $(".btn").click(function () {
            $(".box").removeClass("active");
        })
    })
</script>